The present invention relates to a extremely sturdy and versatile torque limiting device adapted to be used in conjunction with any type of driver tool utilized for the rotational tightening of mechanical fasteners. More particularly, to an accurate torque limiting device designed to be used in a production environment where the driver it is matingly coupled to is operated pneumatically, hydraulicly or electrically at a high speed.
The proper operation of many mechanical components is, to a large degree, dictated by how the parts are assembled. Over tightening of mechanical fasteners can lead to cracked bodies, stretched and weakened bolts, stripped threads, smaller clearance tolerances, and a plethora of other maladies that can seriously affect the operation of the item in question. Similarly, under tightening of mechanical fasteners can have its own, different but potentially disastrous results. For this reason, where the tightness of a mechanical fastener is critical to the overall operation of the item, torque values are experimentally determined and assigned to the individual mechanical fasteners.
Conventional torque limiting devices are separate from the high speed production drivers used to tighten the fastener, and must be interchanged periodically as the desired torque value is approached. This slows the assembly process as conventional torque limiting devices require time to operate. Further, many of the conventional torque limiting devices (such as a torque wrench) indicate the torque level yet do not prevent that level from being exceeded.
The present device is an adjustable torque limiter that can be connected between a high speed driver and the bit that couples to and rotates the mechanical fastener. When the preset torque level is reached, the torque limiter goes into a free wheel mode therein disengaging the rotational drive force from the bit. In this mode the high speed driver may continue to rotate but the bit will remain stationary.
The adjustability of the torque limitation is accomplished by varying the amount of spring force by which a thrust disk (coupled to the high speed driver) frictionally rotates an upper torque body (coupled to the bit) through a intervening set of steel balls that are frictionally captured in an arced (or straight) depression formed in the underside of the upper torque body. When a certain preset torque limit that is being transmitted from the driver to the bit is exceeded, the upper torque body's rotation is retarded with respect to the lower torque body's rotation and the steel balls traverse downward and outwardly along separate arced and rearward ramped radial slots formed thereon a radial torque plate extending normally from the lower torque body, gradually depressing the spring and separating the radial torque plate of the lower thrust body from the thrust disc until the balls exit the distal end of their respective radial paths and enter the outer race of the upper torque body, wherein the bit and upper torque body go into a disengaged or free wheel mode. The unit is reset by a counter rotation of lower torque body with respect to the upper torque body so that the set of balls return to the proximate end of their radial paths in the radial torque plate.
Simply stated, the present torque limiter overcomes all of the stated deficiencies of the traditional prior art through the use of an adjustable force coupling system between the drive and driven ends of the unit. Henceforth, the present invention would fulfill a long felt need in the fabrication industry. This new invention utilizes and combines known and new technologies in a unique and novel configuration to overcome the aforementioned problems therein reducing assembly time and preventing unnecessary damage.